A method of deriving mean arterial pressure of a subject is disclosed. The method comprises (i) receiving (202) data relating to at least one cardiac cycle of a bio-signal from the subject (ii) normalizing the received data relating to the at least one cardiac cycle (iii) calculating (206) an area enclosed by the normalized received data to obtain a normalized area (iv) calculating (208) a heart rate of the subject from the at least one cardiac cycle and (v) deriving (210) the mean arterial pressure from the normalized area and heart rate. A related apparatus is also disclosed.
